A possible role for K+ channels in tumor cell injury. Membrane vesicle shedding and nuclear DNA fragmentation.

Mastocytoma P815 tumor cells subjected to low temperature (O degrees C/l h) and shifted to 22 degrees or 37 degrees C undergo morphological, physiological and biochemical changes which are analogous to those induced by immune effector cells, i.e., changes in cell-surface morphology and membrane permeability, elevated O2 consumption rates and nuclear DNA fragmentation [18-21]. Utilizing this low-temperature shift method for the induction of cell injury, we investigated the possible role of K+ channels in this process. Results show that the two classical K+ channel blockers, tetraethylammonium (TEA) and 4-aminopyridine (4-AP), inhibited the low temperature-induced cell-surface membrane vesicle shedding as well as the nuclear DNA-fragmentation process. These results indicate that K+ channel function is required for tumor-cell injury as manifested by nuclear DNA fragmentation and cell-surface membrane vesicle (MV) shedding.